Method of making catalytic agent for plating bath



United States Patent 3,163,454 ANTI-10D OF MAKING CATALYTIC AGENT FGR PLATEJG BATH Anthony Debe, 18203 (Danterhury Road, Cleveland, Ohio, and Lloyd B. Portzer, deceased, late of leveland, Qhio, by Marietta R. Portzer, executrix, 3212 W. 142ml St, Cleveland, Ohio No Drawing. Filed .llune 23, 1961, Ser. No. 120,442 12 Claims. (Cl. 204d4) The present invention is directed to a method of making a solution containing a derivative of salicylic acid and, more particularly, to a reaction product of salicylic acid and hexamethylene tetramine, otherwise known as hexamine. Whenever the term hexamine appears in the specification and claims that follow, it is intended that this term cover hexamethylene tetramine.

It is an object of the present invention to provide a method of making a solution containing a reaction product of salicylic acid and hexamine, the solution containing also some of the unreacted starting ingredients and being suitable for commercial use in applications such as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths.

It is an object of the present invention to provide a method of making a solution containing a catalytic ingredient for plating baths comprising a derivative of salicylic acid, preferably amino derivatives including p-amino salicylic acid.

It is an object of the present invention to provide a method of making a reaction product of salicyclic acid and hexamine by reacting salicylic acid and hexamine in water at a temperature of about 125 to 190 F. and a pH of about 2.5 to 5.5 for preferably at least about eight hours to provide an acidic reaction mixture, and thereafter reacting the acidic reaction mixture with an alkali metal hydroxide to provide a solution having a pH of about 9 to 12 and preferably 10 /2 to 11 /2. It is an object or" the present invention to provide a method of making a solution containing a reaction product of salicylic acid and hexamine by reacting the two ingredients at a pH of about 2 /2 to /2 to provide a reaction product, andthereafter reacting the product with an alkali metal hydroxide and thereafter adding a salt of an alkali metal and tartaric acid to obtain a resultant reaction product mixture having a pH of at least about /2.

These and other objects of the present invention will be apparent from the specification that follows and the appended claims.

The present invention provides a method of making a catalytic ingredient for an alkali cyanide plating bath, the method comprising the steps of mixing salicylic acid and hexamine, reacting the salicylic acid and hexamine at a pH of about 2 /2 to 5 /2 to form an acidic reaction product, and thereafter reacting the product with potassium hydroxide or other alkali metal hydroxide and, if desired, an alkali metal salt of tartaric acid to produce a solution containing a derivative of salicylic acid. The resultant solution (which can be used as an anode corroder and a smoothing and grain refining agent in, for instance, copper or copper-zinc alloy cyanide plating baths), contains derivatives of salicylic acid including orthoand paraam-ino derivatives thereof, unrea-cted starting ingredients including unreacted salicylic acid and hexamine, and an alkali metal tartrate.

In general, a temperature range of about 145 to 190 F. may be employed to react the salicylic acid and hexamine. It has been found that the reaction is much too slow below 125 F. for commercial use. On the other hand, when a temperature of over 190 F. is used, the

reaction product has a dirty or darker color and is gen- Biddfihd Patented Feb. 2, 1965 erally not desirable for addition to a plating bath or other commercial use.

The preferred temperature range is about 156 to F. in order to obtain the best reaction product of hexamine and salicylic acid. However, for the best results, it has been found that the temperature of around 158 to 168 F. produces the best mixture of amino derivatives of salicylic acid, which heterogeneous mixture of derivatives may be part of the reason why it is so outstanding when used as an anode corroder and a smoothing and grain refining agent.

Generally, when forming the reaction product of hexamine and salicylic acid, a pH of about 3 /2 to 5 /2 should be employed. Usually when the pH is less than 2 /2, apparently the solution is too acidic to form much of the desirable amino derivatives. 0n the other hand, when the pH of the reaction mixture is above 5 /2 and as high as 6, the reactions are not predicable as to the production of valuable derivatives of salicylic acid (whether they be para-amino derivatives or ortho-amino derivatives) and the resultant use of the reaction product in a plating bath does not provide nearly as much anode corrosion activity. As previously indicated, the preferred derivatives are the para-amino salicylic acid derivatives, which have the basic formula of salicylic acid in which the following groups are hooked to the para-amino position (para to the carboxyl group) on the aromatic benzene ring of the salicylic acid: -NH

II II -C- C-NH --NH-R; and NR where R is a residue of the reaction of the hexamethylene tetramine with the salicylic acid and Where R is preferably a short chain alkyl group such as methyl or ethyl, or Where R is methylol.

In combination with the temperature range of 125 to and the pH range of 2 /2 and 5 /2, and preferably 4 to 5, the reaction time should be at least 4 hours and, better, at least 8 hours. In most applications, the reaction time is preferably about 20 to 40 hours, although generally for commercial use, the reaction may be run as long as several days, i.e., about 48 to 72 hours.

During the reaction, the amount of each of the ingredients used is important. Generally, the reaction is made by reacting about one mole of hexamine with about 1 to 4 moles of salicylic acid to provide good amino derivatives, although it is preferred that about 2%. up to as high as about 3% to 3 /2 moles of salicylic acid be used under the above reaction conditions just described.

After the reaction has completed and all the salicylic acid has been dissolved and the gassing has ceased, an alkaline metal hydroxide such as sodium hydroxide and preferably potassium hydroxide should be added for further reaction which brings the pH of the solution up to about 10 to 12. Again, while a pH of 12 may be employed for further reaction with the KOH, a pH of 10 /2 to 11 /2 is highly preferred with the best results being obtained with a narrow pH range of about 10.8 to 11.6. It has been found that when the pH is above 12, the reaction product is much darker and is generally not acceptable as an additive for a plating bath. Likewise, a pH of 8 or less does not provide a desired material, its anode corrosion activity and stability not being enough to justify its use as a cataiytic ingredient in plating baths.

- As to the amount of potassium hydroxide or other alkaline metal hydroxide added, it is preferred that around 2 /2 to 3 moles of potassium hydroxide be used, although generally about 2% to 4 moles may be employed in accordance withthe present invention. Along with the above amount of 'KOH or other alkali metal hydroxide, it is preferred that the reaction be continued at 70 to 190 F. for at least 4 hours and preferably about 8 to 72 hours.

Thus, on the basis of 1200 lbs. of salicylic acid used as one of the starting ingredients, generally 300 to 450 lbs. of hexamine may be used, although the preferred amount is about 380 to 420 lbs. Likewise, the preferred amount of potassium hydroxide is about 380 to 420 lbs. The best results are obtained using about 400 lbs., although generally about 300 to 500 lbs. may be used with the 1200 lbs. of salicylic acid to obtain a reaction product that is useful commercially.

Also, in the above process, it is highly desirable to let the acidic reaction solution stand about 8 to 32 hours and;

preferably 16 to 32 hours before further reacting the solution with the potassium hydroxide.

While adding the potassium hydroxide in accordance with the present invention, it is also preferred that about 1 to 3 moles of an alkaline metal salt of tartaric acid be used, the preferred additive being potassium tartrate although sodium tartrate and potassium bitartrate may also be used. On the basis of starting with 1200 parts by weight of salicylic acid and 400 to 500 parts of hexamine, generally as low as about 400 to 600 up to as high as 1600 to 2000 parts by weight of potassium tartrate may be added although for best results about 1000 to 1500 parts should be used.

During the performance of the process steps just described, it is preferred that the potassium hydroxide and tartrate be added as a premixed solution of about 300 to 500 lbs. of potassium hydroxide and 600 to 1500 lbs. of water along with about 800 to 1000 up to 1200 lbs. of cream of tartar or potassium tartrate.

While not desiring to be strictly held to a particular theory, it is probable that formation of one or more of the derivatives of salicylic acid (including the para-amino derivatives) provide the solution with its anode corroding activity and its grain refining and smoothing ability. Apparently, as previously indicated, derivatives (ortho and para) are formed in which the following groups are attached to the benzene ring of the salicylic acid: amino; carbonyl followed by an amino group; NHR and -NR where R is preferably methyl or even ethyl or where R is methylol. Apparently a minor portion of the mixture is p-amino salicylic acid and it is preferred that only a small portion be the p-amino salicylic acid since it appears that more than 50% p-amino salicylic acid in the mixture of derivatives provides too active a solution. Thus, the above described reaction condition and process steps should be closely followed to obtain a desirable mixture of derivatives.

The following examples are used to illustrate the invention and not to limit it in any way.

Example 1 A reaction product of salicylic acid and hexamine was made by mixing 1200 lbs. of salicylic acid and 400 lbs. of hexamethylene tetramine (hexamine) in an aqueous solution of 300 gallons or about 2490 lbs. of Water. The salicylic acid and hexamine were heated at a temperature of about 160 F. for a period of 24 hours to produce some amino derivatives of salicylic acid. The temperature of the reaction was held within 3 of 160 F. at a pH of 4.3 to 4.5.

As used herein, the pH measurements were made with the glass electrode at 20 C. No correction was made for the sodium ion or ion concentrations.

The batch was vigorously stirred for the first 15 minutes and thereafter the reaction was allowed to proceed for 24 hours, the 24 hour period including an 8 hour period of cooling to room temperature.

Thereafter, 400 lbs. of potassium hydroxide was added to the solution with stirring to bring the pH up to 11 /2 and the reaction continued for 8 hours at 120 F.

The resultant solution was found to be an excellent anode corroder and a fine smoothing and grain refining agent for copper and copper-zinc alloy cyanide plating baths.

4 Example 2 Another reaction product of salicylic acid and hexamine was made by mixing and reacting 1200 lbs. of salicylic acid and 400 lbs. of hexamine were reacted at 170 F. in 2490 parts by weight of water for 24 hours. After settling for 16 hours, the resultant solution was treated with a premixed solution of 615 lbs. potassium hydroxide and 1100 lbs. potassium tartrate dissolved in about 800 lbs. of water. The premixed solution was added to the main batch with stirring and the reaction continued for 4 hours at 160 F. The resultant solution was used as an anode corroder and a smoothing and grain refining agent in zinccopper alloy plating baths with good results.

Example 3 Again, 1200 lbs. of salicylic acid was reacted with hexamine. This time the salicylic acid was reacted with 350 lbs. of hexamethylene tetramine as described in Example 1 at 160 F. for about 24 hours. This solution was allowed to remain standing for 8 hours and thereafter 400 lbs. of potassium hydroxide and 1500 lbs. of potassium tartrate was added to the solution as a premixed additive, the hydroxide and potassium tartrate being dissolved in 172 gallons or about 1430 lbs. of Water. The resultant solution had a pH of about 11 4 and made an excellent anode corroder and a very good smoothing and grain refining agent in copper, zinc and copper-zinc alloy cyanide plating baths.

In the above examples, sodium hydroxide can be used in place of potassium hydroxide and sodium tartrate can be used in place of potassium tartrate to provide similar results. Likewise other suitable reaction conditions of temperature and pH and amounts of ingredients may be used as previously described in place of the actual conditions of temperature and pH and amounts of ingredients used in the above examples to provide a final solution containing amino derivatives of salicylic acid.

What is claimed is:

1. A method of making a solution containing a derivative of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain reluiing agent in alkaline cyanide plating baths, the method comprising the steps of reacting about 1 to 4 moles of salicylic acid with about one mole of hexamethylene tetramine in about 30 to moles of Water at a temperature of about to F. and a pH of about 2 /2 to 5 /2 for at least about 4 hours to provide a reaction mixture, and thereafter reacting about 2% to 4 moles of an alkali metal hydroxide with said reaction mixture for at least about 4 hours to provide a solution containing amino derivatives of salicylic acid and having a pH of at least about 10.

2. A method of making a solution containing a derivative of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of reacting about 1 to 4 moles of salicylic acid with about one mole of hexamethylene tetramine in about 30 to 90 moles of water at a temperature of about 125 to 190 F. and a pH of about 2 /2 to 5 /2 for about 4 to 72 hours to provide a reaction mixture, allowing said reaction mixture to stand for about 1 to 72 hours, and thereafter adding about 20 to 60 moles of water and about 2 to about 4 moles of an alkali metal hydroxide and reacting the mixture with the hydroxide for at least about 4 hours to provide a solution having a pH of about 10 to 12.

3. A method of making a solution containing a derivative of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comcomprising the steps of reacting about 2 /2 to 3% moles of salicylic acid with about one mole of hexamine in about 30 to 90 moles of Water at a temperature of about 125 to 190 F. and a pH of about 4 to 5 for about 20 to 40 hours to provide a reaction mixture, cooling said mixture to room temperature, allowing said mixture to stand for at least about 8 hours, reacting the mixture with about 2% to about 4 moles of an alkali metal hydroxide at about 70 to 180 F. for about 8 to 72 hours, and thereafter adding about 1 to 3 moles of a salt of an alkali metal and tartaric acid to provide a solution containing a derivative of salicylic acid.

4. A method as defined in claim 1 in which the alkali hydroxide is potassium hydroxide.

5. A method as defined in claim 3 in which the alkali hydroxide is potassium hydroxide and the salt is potassium tartrate.

6. A method of making a solution containing a reaction product of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of mixing about 1000 to 1400 parts by weight of salicylic acid and about 300 to 500 parts by weight of hexamine in about 2300 to 3600 parts by weight of water at about 125 to 190 F. and a pH of about 2% to 5 /2 for at least about 8 hours and until substantially all the solid salicylic acid is used up and substantially all the gassing is completed, and thereafter adding thereto and reacting therewith a premixed solution of about 800 to 1600 parts by weight of sodium tartrate and about 300 to 625 parts by weight of potassium hydroxide in water for about 8 to 72 hours to provide a solution containing a reaction product of salicylic acid.

7. A method of making a solution containing a reaction product of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of mixing about 1000 to 1400 parts by weight of salicylic acid and about 300 to 500 parts by weight of hexamine in about 2300 to 3600 parts by weight of water at about 158 to 168 and a pH of about 4.2 to 4.5 for about 20 to 40 hours, and thereafter mixing therein and reacting therewith a premixed solution of about 800 to 1200 parts by weight of potassium tartrate and about 300 to 500 parts by weight of potassium hydroxide in about 400 to 1500 parts by weight of water for about 8 to 72 hours to provide a solution having a pH of about 10 /2 to 12 and containing a reaction product of salicylic acid.

8. A method of making a solution containing derivatives of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of reacting about 1200 parts by weight of salicylic acid with about 300 to 500 parts by weight of hexamine in about 2300 to 2600 parts by weight of water at a temperature of about 158 to 168 F. at a pH of about 4 to 5 for about 20 to 40 hours until substantially all the solid salicylic acid is used up and substantially all the gassing is completed to form a reaction mixture, and

reacting the mixture with about 300 to 500 parts by weight of an alkali metal hydroxide for about 8 to 72 hours to raise the pH to about 9 to 12 to provide a solution having a pH of at least about 10 /2 and containing a derivative of salicylic acid.

9. A method as defined in claim 8 in which the alkali metal hydroxide is potassium hydroxide.

10. A method of making a solution containing derivatives of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of reacting about 1200 parts by weight of salicylic acid with about 300 to 500 parts by weight of hexamine in about 2300 to 2600 parts by weight of water at a temperature of about 158 to 168 F. at a pH of about 4 to 5 for about 20 to 40 hours until substantially all the solid salicylic acid is used up and substantially all the gassing is completed to form a reaction mixture, allowing the reaction mixture to stand for about 16 to 32 hours before reacting the mixture with additional alkali metal hydroxide, and reacting the mixture with about 300 to 500 parts by weight of an alkali metal hydroxide and about 1000 to 1200 parts of an alkali metal tartratc for about 8 to 72 hours to raise the pH to about 9 to 12 to provide a solution having a pH of at least about 10 and containing a derivative of salicylic acid.

11. A method as defined in claim 10 in which the alkali metal tartrate is potassium tartrate.

12. A method of making a solution containing a derivative of salicylic acid, said solution being suitable for use as an anode corroder and a smoothing and grain refining agent in alkaline cyanide plating baths, the method comprising the steps of reacting about 1200 parts by weight of salicylic acid and 400 parts by weight of hexamine in about 2490 parts by weight of water at about to F. at a pH of about 4.1 to 4.6 for about 8 to 72 hours to form a solution containing para-amino derivatives of salicylic acid, and thereafter adding to said solution a mixture comprising about 1100 parts by weight of potassium tartrate and 400 parts by weight of potassium hydroxide in about 1000 parts by weight of water and reacting the resultant mixture for about 8 to 72 hours.

References Cited by the Examiner UNITED STATES PATENTS 569,429 10/96 Schifif 260248.5 1,133,916 3/15 Boedecker 260-2485 2,346,562 4/44 De Long 252156 OTHER REFERENCES Chemical Abstracts, vol. 33, 1939, pub. American Chem. Soc.; article by P. Bouchereau, page 8565, column 1.

Chemical Trade Names and Commercial Synonyms, Haynes, pub. D. Van Nostrand (1955), page 217.

JULIUS GREENWALD, Primary Examiner. 

1. A METHOD OF MAKING A SOLUTION CONTAINING A DERIVATIVE OF SALICYLIC ACID, SAID SOLUTION BEING SUITABLE FOR USE AS AN ANODE CORRODER AND A SMOOTHING AND GRAIN REFINING AGENT IN ALKALINE CYANIDE PLATING BATHS, THE METHOD COMPRISING THE STEPS OF REACTING ABOUT 1 TO 4 MOLES OF SALICYLIC ACID WITH ABOUT ONE MODE OF HEXAMETHYLENE TETRAMINE IN ABOUT 30 TO 90 MOLES OF WATER AT A TEMPERATURE OF ABOUT 125* TO 190*F. AND A PH OF ABOUT 2 1/2 TO 5 1/2 FOR AT LEAST ABOUT 4 HOURS TO PROVIDE A REACTION MIXTURE, AND THEREAFTER REACTING ABOUT 2 1/4 TO 4 MOLES OF AN ALKALI METAL HYDROXIDE WITH SAID REACTIN MIXTURE FOR AT LEAST ABOUT 4 HOURS OT PROVIDE A SOLUTION CONTAIING AMINO DERIVATIVES OF SALICYLIC ACID AND HAVING A PH OF AT LEAST ABOUT
 10. 